It's been a very long time since there has been an update to the marketplace, but I can say that you're going to be seeing quite a few within the future. For that purpose, this thread will be reused so I don't have to make tons of threads.
Currently I would like to let you all know that the Elixir of Fertility is now officially stocking in the Mage's Brewery. I originally placed it up for auction to get a good sight of what prices would do well, as well as to possibly let a user or two get it for cheaper than it would actually cost. Obviously this is not going to be a cheap potion considering the possibility of getting two custom Kuhnas(Which used to cost $15 each if you bought them from the giftshop) out of a breeding. I will also be updating the Marketplace FAQ shortly to contain any questions that have thus-far been asked about how the potion works.